1. Field of the Invention
The present invention generally relates to a regeneration control system for an exhaust filter. More specifically, the present invention relates to a regeneration control system for oxidizing exhaust particulate matter collected by an exhaust filter.
2. Background Information
In internal combustion engines such as diesel engines, an exhaust gas recirculating system (EGR system) is widely used wherein a part of the exhaust gas is recirculated to lower the combustion temperature in order to reduce discharge of nitrogen oxide (NOx). Some prior exhaust systems for diesel engines often include a diesel particulate filter (DPF) and a NOx trapping catalytic converter that are disposed in an exhaust passage. The diesel particulate filter (DPF) traps particulate matters (PM) in the exhaust gas, while the NOx trapping catalytic converter traps NOx in the exhaust gas when an air-fuel ratio in the exhaust gas is in a lean range and purifies the trapped NOx when the air-fuel ratio is in a rich range. The particulate matters deposited in the diesel particulate filter (DPF) and the NOx deposited in the NOx trapping catalytic converter are respectively purified at a predetermined period of time.
The diesel particulate filter (DPF) is provided in the exhaust system for collecting particulate matter. The diesel particulate filter (DPF) is regenerated by combusting the particulates collected by the diesel particulate filter (DPF) at regular intervals through exhaust temperature manipulation or the like. One example of an internal combustion engine having a NOx trapping catalytic converter provided in the exhaust system for cleaning NOx discharged from the engine is disclosed in Japanese Laid-Open Patent Publication No. 2000-179326.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved regeneration control system. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.